An output voltage control circuit and its constant voltage output system

Abstract

The present application provides an output voltage control circuit and its constant voltage output system. The output voltage control circuit includes a load current compensation circuit, an input voltage compensation circuit, a compensation voltage generation circuit, and an error amplification circuit. In this solution, the compensation voltage generation circuit generates a compensation voltage based on the load compensation current transmitted by the load current compensation circuit, the input voltage compensation current transmitted by the input voltage compensation circuit, and a preset reference voltage, and transmits the compensation voltage to the error amplification circuit. Furthermore, based on the error signal output by the error amplification circuit, the influence of the change in the load current and the change in the input voltage on the output voltage is eliminated or reduced, so as to control the output voltage of the power supply to be constantly output.

Description

Technical Field

[0001] This application relates to the technical field of constant-voltage output of power supplies. Specifically, it relates to an output voltage control circuit and its constant-voltage output system. Background Art

[0002] Currently, the output voltage of a power supply is generally affected by changes in the input voltage (i.e., the bus voltage). In addition to being affected by changes in the input voltage, changes in the load current also affect the output voltage value. Generally, an increase in the input bus voltage or an increase in the load current will cause the output voltage to decrease, resulting in a large fluctuation in the output voltage of the power supply, which may damage the load or circuit components. Summary of the Invention

[0003] The purpose of the embodiments of this application is to provide an output voltage control circuit and its constant-voltage output system to eliminate or reduce the influence of bus voltage changes or load current changes on the output voltage, thereby realizing the constant-voltage output of the power supply.

[0004] In a first aspect, the present invention provides an output voltage control circuit, including: a compensation circuit and an error amplification circuit. The compensation circuit includes a load current compensation circuit and a compensation voltage generation circuit; the load current compensation circuit is used to generate a load compensation current according to the error signal output by the error amplification circuit and transmit the load generated current to the compensation voltage generation circuit; the compensation voltage generation circuit is used to generate a load compensation voltage according to a preset reference voltage and the load compensation current and transmit the load compensation voltage to the inverting input terminal of the error amplification circuit; the error amplification circuit is used to output a corresponding error signal according to the output voltage received by the non-inverting input terminal and the load compensation voltage received by the inverting input terminal, and the error signal is used to correspondingly adjust the output voltage of the modulation circuit to control the constant output of the output voltage.

[0005] In the output voltage control circuit designed above, when the load current changes, the output voltage shows an inverse correlation with the load current. The error signal output by the error amplification circuit shows a positive correlation with the output voltage. The load current compensation circuit generates a load compensation current with a positive correlation according to the error signal output by the error amplification circuit. Then, the compensation voltage generation circuit generates a load compensation voltage with an inverse correlation with the load compensation current based on a preset reference voltage and the load compensation current and outputs it to the inverting input terminal of the error amplification circuit, so that the voltage at the non-inverting input terminal of the error amplification circuit changes synchronously with the change of the load compensation voltage at the inverting input terminal, and then outputs an error signal that changes positively with the load compensation voltage. Furthermore, the output error signal is positively correlated with the load current. Furthermore, the output voltage adjusted based on the error signal is also positively correlated with the load current. In this way, the inverse correlation change of the original output voltage due to the change of the load current is compensated, so that the output voltage remains basically unchanged, thereby eliminating or reducing the influence of the change of the load current on the output voltage, and further realizing the constant voltage output of the power supply.

[0006] In an alternative embodiment of the first aspect, the input terminal of the load current compensation circuit is connected to the output terminal of the error amplification circuit, the output terminal of the load current compensation circuit is connected to the input terminal of the compensation voltage generation circuit, the output terminal of the compensation voltage generation circuit is connected to the inverting input terminal of the error amplification circuit, the non-inverting input terminal of the error amplification circuit is used to sample the output voltage, and the output terminal of the error amplification circuit is also used to be connected to a modulation circuit.

[0007] In an alternative embodiment of the first aspect, the compensation voltage generation circuit includes a compensation error amplifier, a compensation resistor R1, a compensation resistor R2, and a compensation controllable switch tube; the non-inverting input terminal of the compensation error amplifier is used to receive the preset reference voltage, the inverting input terminal of the compensation error amplifier is respectively connected to the first terminal of the compensation resistor R1, the first terminal of the compensation resistor R2, and the output terminal of the load current compensation circuit, the second terminal of the compensation resistor R1 is grounded, the second terminal of the compensation resistor R2 is respectively connected to the inverting input terminal of the error amplification circuit and the first terminal of the compensation controllable switch tube, the output terminal of the compensation error amplifier is connected to the control terminal of the compensation controllable switch tube, and the second terminal of the compensation controllable switch tube is connected to an external power supply; the compensation error amplifier is used to clamp the preset reference voltage to the first terminal of the compensation resistor R1 and form a first compensation current between the inverting input terminal of the compensation error amplifier, the compensation resistor R1, and the ground terminal, so as to generate a load compensation partial voltage according to the current difference between the first compensation current and the load compensation current and the compensation resistor R2, and thus generate the load compensation voltage according to the load compensation partial voltage and the preset reference voltage and transmit it to the inverting input terminal of the error amplification circuit.

[0008] In an alternative embodiment of the first aspect, the load current compensation circuit includes a load compensation error amplifier, a load compensation resistor R3, a load compensation controllable switch tube, and a load compensation current mirror; the positive input terminal of the load compensation error amplifier is connected to the output terminal of the error amplification circuit, the negative input terminal of the load compensation error amplifier is grounded through the load compensation resistor R3, the output terminal of the load compensation error amplifier is connected to the control terminal of the load compensation controllable switch tube, the first terminal of the load compensation controllable switch tube is connected to the negative input terminal of the load compensation error amplifier, and the second terminal of the load compensation controllable switch tube is connected to the load compensation voltage generation circuit through the load compensation current mirror; the load compensation error amplifier is configured to clamp the voltage of the error signal to the first terminal of the load compensation controllable switch tube, so as to form a second compensation current on the load compensation resistor R3 and the load compensation controllable switch tube branch and output it to the load compensation current mirror; the load compensation current mirror is configured to generate the load compensation current according to the corresponding current mirror ratio and the second compensation current.

[0009] In an alternative embodiment of the first aspect, the output voltage control circuit further includes a modulation circuit, the input terminal of the modulation circuit is connected to the output terminal of the error amplification circuit, and the output terminal of the modulation circuit is configured to be connected to the controllable switch tube; the modulation circuit is configured to output a corresponding modulation signal according to the sampled voltage of the peak current and the error signal, and the modulation signal is used to adjust the duty cycle of the controllable switch tube, so as to perform corresponding adjustment on the output voltage to achieve constant voltage output, wherein the duty cycle of the controllable switch tube is positively correlated with the modulation signal.

[0010] In an alternative embodiment of the first aspect, the load compensation current is inversely correlated with the load current, the load compensation voltage is inversely correlated with the load compensation current, and the error signal and the output voltage are positively correlated with the load compensation voltage.

[0011] In an alternative embodiment of the first aspect, the compensation circuit further includes an input voltage compensation circuit; the input voltage compensation circuit is configured to generate an input voltage compensation current according to the input voltage and transmit the input voltage compensation current to the compensation voltage generation circuit; the compensation voltage generation circuit is further configured to generate a compensation voltage according to the preset reference voltage, the load compensation current, and the input voltage compensation current and transmit the compensation voltage to the negative input terminal of the error amplification circuit.

[0012] In the implementation of the above design, the load current compensation circuit generates a load compensation current with an anti-correlated change according to the change of the load current, and the input voltage compensation circuit generates an input voltage compensation current with an anti-correlated change according to the change of the input voltage. Then, the compensation voltage generation circuit generates a compensation voltage that is anti-correlated with the load compensation current and the input voltage compensation current based on a preset reference voltage, the load compensation current, and the input voltage compensation current, and then outputs the compensation voltage to the inverting input terminal of the error amplification circuit, so that the error amplification circuit outputs an error signal that is positively correlated with the compensation voltage. Furthermore, based on the error signal, the output voltage compensates for the positive correlation changes corresponding to the load current change and the input voltage change, thus compensating both the anti-correlated change of the output voltage originally presented due to the change of the input voltage and the anti-correlated change of the output voltage presented due to the change of the load current, making the output voltage basically remain unchanged, thereby eliminating or reducing the influence of the changes in the input voltage and the load current on the output voltage, and further realizing the constant voltage output of the power supply.

[0013] In a second aspect, the present invention provides an output voltage control circuit, including: a compensation circuit and an error amplification circuit, where the compensation circuit includes an input voltage compensation circuit and a compensation voltage generation circuit; the input voltage compensation circuit is configured to generate an input voltage compensation current according to the input voltage and transmit the input voltage compensation current to the compensation voltage generation circuit, and the input voltage is a sampled voltage corresponding to the bus voltage; the compensation voltage generation circuit is configured to generate an input compensation voltage according to a preset reference voltage and the input voltage compensation current and transmit the input compensation voltage to the inverting input terminal of the error amplification circuit; the error amplification circuit is configured to output a corresponding error signal according to the output voltage received at the non-inverting input terminal and the input compensation voltage received at the inverting input terminal, and the error signal is used to perform corresponding adjustment on the output voltage of the modulation circuit to control the constant output of the output voltage.

[0014] In the output voltage control circuit of the above design, the input voltage compensation circuit generates an input voltage compensation current that is anti-correlated with the output voltage according to the input voltage. Then, based on the input compensation current, the compensation voltage generation circuit generates an input compensation voltage that is anti-correlated with the input compensation current and outputs the input compensation voltage to the inverting input terminal of the error amplification circuit, so that the error amplification circuit outputs an error signal that is positively correlated with the input compensation voltage. Furthermore, the output voltage adjusted based on the error signal is also positively correlated with the input compensation voltage, thus compensating the anti-correlated change of the output voltage originally presented due to the change of the input voltage, making the output voltage basically remain unchanged, thereby eliminating or reducing the influence of the change of the input voltage on the output voltage, and further realizing the constant voltage output of the power supply.

[0015] In an alternative embodiment of the second aspect, the input voltage compensation circuit includes a voltage compensation error amplifier, a voltage compensation resistor R4, a voltage compensation controllable switch transistor, a voltage compensation first current mirror, a voltage compensation second current mirror, and a fixed current source; the positive input terminal of the voltage compensation error amplifier is used to receive the input voltage, the negative input terminal of the voltage compensation error amplifier is grounded through the voltage compensation resistor R4, and the output terminal of the voltage compensation error amplifier is connected to the control terminal of the voltage compensation controllable switch transistor; the first terminal of the voltage compensation controllable switch transistor is grounded through the voltage compensation resistor R4, the second terminal of the voltage compensation controllable switch transistor is connected to the input terminal of the voltage compensation first current mirror, the output terminal of the voltage compensation first current mirror is respectively connected to the voltage compensation second current mirror and the first terminal of the fixed current source, the second terminal of the fixed current source is grounded, and the output terminal of the voltage compensation second current mirror is connected to the input terminal of the compensation voltage generation circuit.

[0016] In a third aspect, the present invention provides a constant voltage output system, including a rectification module, a constant voltage control chip, and a buck conversion module. The constant voltage control chip includes the output voltage control circuit according to any one of the first aspect or the second aspect; the input terminal of the rectification module is used to receive alternating current, the output terminal of the rectification module is coupled to the constant voltage control chip, a controllable switch transistor is provided in the constant voltage control chip, the output terminal of the rectification module is coupled to the buck conversion module through the controllable switch transistor, the output terminal of the buck conversion module is connected to the positive input terminal of the error amplification circuit, and the output terminal of the error amplification circuit is connected to the controllable switch transistor to control the constant output of the output voltage.

[0017] In the constant voltage output system designed in the third aspect, since the constant voltage control chip of the designed constant voltage output system includes the output voltage control circuit in any one of the first aspect or the second aspect, therefore, the designed constant voltage output system can eliminate or reduce the influence of the load current and / or the input voltage on the output voltage, and achieve a more accurate constant voltage output of the power supply. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required to be used in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is the first structure diagram of the output voltage control circuit provided by the first embodiment of the present application;

[0020] Figure 2 The second structural diagram of the output voltage control circuit provided by the first embodiment of the present application;

[0021] Figure 3 The third structural diagram of the output voltage control circuit provided by the first embodiment of the present application;

[0022] Figure 4 The fourth structural diagram of the output voltage control circuit provided by the first embodiment of the present application;

[0023] Figure 5 The first structural diagram of the output voltage control circuit provided by the second embodiment of the present application;

[0024] Figure 6 The second structural diagram of the output voltage control circuit provided by the second embodiment of the present application;

[0025] Figure 7 The third structural diagram of the output voltage control circuit provided by the second embodiment of the present application;

[0026] Figure 8 The fourth structural diagram of the output voltage control circuit provided by the second embodiment of the present application;

[0027] Figure 9 The first structural diagram of the output voltage control circuit provided by the third embodiment of the present application;

[0028] Figure 10 The second structural diagram of the output voltage control circuit provided by the third embodiment of the present application;

[0029] Figure 11 The schematic diagram of the constant voltage output system structure provided by the fourth embodiment of the present application.

[0030] Icon: 1 - Rectification module; 2 - Constant voltage control chip; 3 - Buck conversion module; 4 - Output voltage control circuit; 10 - Compensation circuit; 101 - Load current compensation circuit; 1011 - Load compensation error amplifier; 1012 - Load compensation controllable switch tube; 1013 - Load compensation current mirror; 102 - Compensation voltage generation circuit; 1021 - Compensation error amplifier; 1022 - Compensation controllable switch tube; 110 - Input voltage compensation circuit; 1101 - Input voltage sampling sub - circuit; 1102 - Voltage compensation error amplifier; 1103 - Voltage compensation controllable switch tube; 1104 - Voltage compensation first current mirror; 1105 - Voltage compensation second current mirror; 1106 - Constant current source; 20 - Error amplification circuit; 30 - Modulation circuit; 40 - Voltage sampling circuit; Q1 - Controllable switch tube. Detailed implementation manners

[0031] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application.

[0032] First Embodiment

[0033] This embodiment provides an output voltage control circuit for eliminating or reducing the influence of the change in load current on the output voltage, thereby realizing the constant voltage and stable output of the power supply.

[0034] As Figure 1 shown, the output voltage control circuit includes a compensation circuit 10 and an error amplification circuit 20. The compensation circuit 10 includes a load current compensation circuit 101 and a compensation voltage generation circuit 102.

[0035] The input end of the load current compensation circuit 101 is connected to the output end of the error amplification circuit 20. The output end of the load current compensation circuit 101 is connected to the input end of the compensation voltage generation circuit 102. The output end of the compensation voltage generation circuit 102 is connected to the inverting input end of the error amplification circuit 20. The non-inverting input end of the error amplification circuit 20 is used to sample the output voltage Vout. The output voltage Vout can be the output voltage of the power supply chip or the voltage output to the power supply load. The output end of the error amplification circuit 20 is used to be connected to the modulation circuit 30. Among them, the error amplification circuit 20 can be an error amplifier as Figure 1 shown, or other forms of circuits with an error amplifier.

[0036] For the output voltage control circuit designed above, when the load current changes, the output voltage Vout sampled by the error amplification circuit 20 shows a change inversely related to the load current. The error signal Veao output by the error amplification circuit 20 shows a change positively related to the output voltage Vout sampled by it. For example, when the load current becomes smaller, the output voltage Vout sampled by the non-inverting input end of the error amplification circuit 20 increases, and the error signal Veao output by the error amplification circuit 20 also increases.

[0037] Since the input end of the load current compensation circuit 101 is connected to the output end of the error amplification circuit 20, the load current compensation circuit 101 can collect the error signal Veao output by the error amplification circuit 20. The load current compensation circuit 101 can generate a load compensation current I1 according to the error signal Veao and transmit the load compensation current I1 to the compensation voltage generation circuit 102. The compensation voltage generation circuit 102 generates a load compensation voltage Vref2 according to the load compensation current I1 and a preset reference voltage and transmits the load compensation voltage Vref2 to the inverting input end of the error amplification circuit 20.

[0038] Among them, the load compensation current I1 changes in a positive correlation with the error signal Veao. For example, when the error signal Veao increases, the load compensation current I1 also increases. The load compensation voltage Vref2 changes in an inverse correlation with the load compensation current I1. For example, when the load compensation current I1 increases, the load compensation voltage Vref2 decreases.

[0039] As a possible implementation, the inverse correlation between the load compensation voltage Vref2 and the load compensation current I1 can be achieved in the following manner, as Figure 2 shown, the compensation voltage generation circuit 102 includes a compensation error amplifier 1021, a compensation resistor R1, a compensation resistor R2, and a compensation controllable switch 1022.

[0040] The positive input terminal of the compensation error amplifier 1021 is used to receive a preset reference voltage Vref1. The negative input terminal of the compensation error amplifier 1021 is connected to the first terminal of the compensation resistor R1, the first terminal of the compensation resistor R2, and the output terminal of the load current compensation circuit 101 respectively. The second terminal of the compensation resistor R1 is grounded. The second terminal of the compensation resistor R2 is connected to the negative input terminal of the error amplification circuit 20 and the first terminal of the compensation controllable switch 1022 respectively. The output terminal of the compensation error amplifier 1021 is connected to the control terminal of the compensation controllable switch 1022. The first terminal of the compensation controllable switch 1022 is connected to an external power supply VDD. Among them, the compensation controllable switch 1022 can be a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). On this basis, the second terminal of the compensation controllable switch 1022 is the source electrode, the first terminal of the compensation controllable switch 1022 is the drain electrode, and the control terminal of the compensation controllable switch 1022 is the gate electrode. In addition to being a MOSFET, the compensation controllable switch 1022 can also be other forms of controllable switches, such as an Insulated Gate Bipolar Transistor (IGBT), etc.

[0041] The compensation voltage generation circuit 102 designed above, the compensation error amplifier 1021 clamps the preset reference voltage Vref1 received at its non-inverting input terminal to the first end of R1, so as to form a first compensation current Ia between the inverting input terminal of the compensation error amplifier 1021, the compensation resistor R1 and the ground terminal, and form a compensation generation current Ib between the external power supply VDD, the compensation controllable switch 1022 and the compensation resistor R2. Since the output terminal of the load current compensation circuit 101 is connected to the first end of the compensation resistor R2 (which is also the first end of the compensation resistor R1), therefore, the load compensation current I1 generated by the load current compensation circuit 101 flows into from the first end of the compensation resistor R2, and further makes the compensation generation current Ib equal to the current difference between the first compensation current Ia and the load compensation current I1, that is, Ib = Ia - I1.

[0042] Since the second end of the compensation resistor R2 is connected to the inverting input terminal of the error amplification circuit 20, therefore, the formed load compensation voltage Vref2 = Vref1 + Ib * R2 = Vref1 + (Ia - I1) * R2, and further generates a load compensation voltage Vref2 that is inversely related to the load compensation current I1.

[0043] As a possible implementation manner, the load compensation current I1 can be positively correlated with the error signal Veao in the following way, such as Figure 3 shown, the load current compensation circuit 101 includes a load compensation error amplifier 1011, a load compensation resistor R3, a load compensation controllable switch 1012 and a load compensation current mirror 1013.

[0044] The non-inverting input terminal of the load compensation error amplifier 1011 is connected to the output terminal of the error amplification circuit 20, the inverting input terminal of the load compensation error amplifier 1011 is grounded through the load compensation resistor R3, the output terminal of the load compensation error amplifier 1011 is connected to the control terminal of the load compensation controllable switch 1012, the first end of the load compensation controllable switch 1012 is connected to the inverting input terminal of the load compensation error amplifier 1011, the second end of the load compensation controllable switch 1012 is connected to the compensation voltage generation circuit 102 through the load compensation current mirror 1013. Specifically, the output terminal of the load compensation current mirror 1013 is connected to the first end of the compensation resistor R2 in the compensation voltage generation circuit 102. Among them, the load compensation controllable switch 1012 can also be a MOS transistor or other forms of controllable switches.

[0045] For the load current compensation circuit 101 designed above, the error signal Veao output by the error amplifier circuit 20 is transmitted to the load compensation error amplifier 1011. The load compensation error amplifier 1011 clamps the error signal to the first end of the load compensation current R3, so that a second compensation current I2 is formed on the load compensation resistor R3, the load compensation controllable switch 1012, and the power supply VDD branch, where I2 = Veao / R3; this second compensation current I2 forms the aforementioned load compensation current I1 through the load compensation current mirror 1013. Assuming the ratio of the load compensation current mirror 1013 is K1, then I1 = I2 * K1.

[0046] Based on the above example, if the error signal Veao increases, since the load compensation resistor R3 remains unchanged, the generated second compensation current I2 also increases. Since the ratio of the load compensation current mirror 1013 is K1 and it is a positive number, therefore, the generated load compensation current I1 also increases, and thus the load compensation current I1 is positively correlated with the error signal Veao.

[0047] In the above way, the load compensation current I1 can be positively correlated with the error signal Veao, and the load compensation voltage Vref2 is inversely correlated with the load compensation current I1. The load compensation voltage Vref2 is output to the inverting input terminal of the error amplifier circuit 20. Since the non-inverting input terminal and the inverting input terminal of the error amplifier circuit 20 change synchronously, the error signal Veao output by the error amplifier circuit 20 is also positively correlated with the load compensation voltage Vref2 received by the inverting input terminal. Furthermore, the modulation circuit 30 controls the output voltage positively correlated with the error signal Veao based on the error signal Veao, and thus compensates for the output voltage that changes inversely with the load current due to the change of the load current, so that the output voltage remains basically unchanged, thereby eliminating or reducing the influence of the change of the load current on the output voltage, and further realizing the constant voltage output of the power supply.

[0048] According to the above principle, the following is illustrated by examples:

[0049] When the load current decreases, the output voltage Vout increases. The increase in the output voltage Vout causes the output signal Veao of the error amplification circuit 20 to increase. Since the load compensation current I1 is positively correlated with the output signal Veao, the load compensation current I1 also increases. Since the load compensation voltage Vref2 is inversely correlated with the load compensation current I1, the load compensation voltage Vref2 decreases. Since the voltage at the positive input terminal of the error amplification circuit 20 changes synchronously with the load compensation voltage Vref2 at the negative input terminal, the voltage received at the positive input terminal of the error amplification circuit 20 decreases, causing the output signal Veao of the error amplification circuit 20 to decrease. As a result, the output voltage is correspondingly adjusted downward based on the output signal Veao, reducing the output voltage, thereby compensating for the increase in the output voltage due to the decrease in the load current, and thus controlling the output voltage to remain basically unchanged, eliminating or reducing the impact of the change in the load current on the output voltage, and further controlling the constant voltage output of the power supply. It should be noted here that the above example is for the scenario where the load current decreases. The principle for the scenario where the load current increases is similar to the above and will not be elaborated here.

[0050] In an alternative embodiment of the present embodiment, as Figure 4 shown, the output voltage control circuit may further include a modulation circuit 30. The input terminal of the modulation circuit 30 is connected to the output terminal of the error amplification circuit 20, and the output terminal of the modulation circuit 30 is used to connect to the controllable switch tube Q1.

[0051] As an implementation manner, the modulation circuit 30 may be a comparator. The first input terminal of the comparator is connected to the output terminal of the error amplification circuit 20. The first input terminal of the comparator receives the error signal Veao output by the error amplification circuit 20 superimposed with the sampled voltage VL of the peak current to form a ramp compensation voltage signal RAW. The slope of the ramp compensation voltage signal RAW increases as Veao increases. The second terminal of the comparator is used to receive a second preset reference voltage Vref3. The comparator outputs a modulation signal d based on the ramp compensation voltage RAW and the second preset reference voltage Vref3. The modulation signal d decreases as the slope of the ramp compensation voltage signal RAW increases. Therefore, the modulation signal d is inversely correlated with the error signal Veao.

[0052] On the above basis, when the load current decreases, the output voltage Vout increases. The increase in the output voltage Vout causes the output signal Veao of the error amplification circuit 20 to increase. On the one hand, the increase in the output signal Veao causes the slope of the ramp compensation voltage signal RAW formed by superimposing it with the sampled voltage VL of the peak current to increase, thereby causing the modulation signal d to decrease. The decreased modulation signal d causes the duty cycle of the controllable switch tube Q1 to decrease, and further causes the output voltage controlled by the controllable switch tube Q1 to decrease;

[0053] On the other hand, the increased output signal Veao is transmitted to the load current compensation circuit 101 to generate a load compensation current I1. Since the load compensation current I1 is positively correlated with the output signal Veao, the load compensation current I1 also increases. Since the load compensation voltage Vref2 is inversely correlated with the load compensation current I1, the load compensation voltage Vref2 decreases. Since the voltage at the positive input terminal of the error amplification circuit 20 changes synchronously with the load compensation voltage Vref2 at the negative input terminal, the voltage at the positive input terminal of the error amplification circuit 20 decreases, causing the output signal Veao of the error amplification circuit 20 to decrease, thereby controlling the output voltage to remain constant by adjusting the magnitude of the modulation signal d.

[0054] In an alternative embodiment of the present embodiment, as Figure 4 shown, the output voltage control circuit may further include a voltage sampling circuit 40. The voltage sampling circuit 40 is coupled to the positive input terminal of the error amplification circuit 20, so that the positive input terminal of the error amplification circuit 20 samples the output voltage through the voltage sampling circuit 40.

[0055] As a possible implementation, the voltage sampling circuit 40 may include a sampling resistor R10 and a sampling resistor R11. The first end of the sampling resistor R10 is used to receive the output voltage. The second end of the sampling resistor R10 is grounded through the sampling resistor R11, and the second end of the sampling resistor R10 is connected to the positive input terminal of the error amplification circuit 20, so that the positive input terminal of the error amplification circuit 20 samples the output voltage through the voltage sampling circuit 40.

[0056] Based on the above, the voltage sampled at the positive input terminal of the error amplification circuit 20 may be a voltage division Vfb of the output voltage Vout, and the voltage division Vfb changes synchronously with the output voltage Vout.

[0057] Second Embodiment

[0058] This embodiment provides an output voltage control circuit. The output voltage control circuit in this embodiment can eliminate or reduce the influence of the change in the input voltage on the output voltage, and thus achieve a constant voltage output of the power supply.

[0059] As Figure 5 shown, the output voltage control circuit includes a compensation circuit 10 and an error amplification circuit 20. In this embodiment, the compensation circuit 10 includes an input voltage compensation circuit 110 and a compensation voltage generation circuit 102. The input terminal of the input voltage compensation circuit 110 is used to sample the input voltage, and the input voltage is the sampled voltage corresponding to the bus voltage.

[0060] The output terminal of the input voltage compensation circuit 110 is connected to the input terminal of the compensation voltage generation circuit 102. The output terminal of the compensation voltage generation circuit 102 is connected to the inverting input terminal of the error amplification circuit 20. The non-inverting input terminal of the error amplification circuit 20 is used to sample the output voltage, and the output terminal of the error amplification circuit 20 is used to be connected to the modulation circuit 30.

[0061] In the output voltage control circuit designed above, the input voltage Vm is collected by the input voltage compensation circuit 110. The input voltage compensation circuit 110 generates an input voltage compensation current I3 according to the input voltage Vm. Among them, the input voltage compensation current I3 is inversely related to the input voltage Vm.

[0062] As a possible implementation manner, the inverse correlation between the input voltage compensation current I3 and the input voltage Vm can be achieved in the following manner. For example, Figure 6 as shown, the input voltage compensation circuit 110 includes an input voltage sampling sub-circuit 1101, a voltage compensation error amplifier 1102, a voltage compensation resistor R4, a voltage compensation controllable switch tube 1103, a voltage compensation first current mirror 1104, a voltage compensation second current mirror 1105, and a constant current source 1106.

[0063] The non-inverting input terminal of the voltage compensation error amplifier 1102 samples the input voltage Vm through the input voltage sampling sub-circuit 1101. The inverting input terminal of the voltage compensation error amplifier 1102 is grounded through the voltage compensation resistor R4. The output terminal of the voltage compensation error amplifier 1102 is connected to the control terminal of the voltage compensation controllable switch tube 1103.

[0064] The first terminal of the voltage compensation controllable switch tube 1103 is grounded through the voltage compensation resistor R4. The second terminal of the voltage compensation controllable switch tube 1103 is connected to the input terminal of the voltage compensation first current mirror 1104. The output terminal of the voltage compensation first current mirror 1104 is respectively connected to the first terminal of the voltage compensation second current mirror 1105 and the constant current source 1106. The second terminal of the constant current source 1106 is grounded. The output terminal of the voltage compensation second current mirror 1105 is connected to the input terminal of the compensation voltage generation circuit 102.

[0065] In the input voltage compensation circuit 110 designed above, the voltage compensation error amplifier 1102 clamps the sampled input voltage Vm to the upper end of the voltage compensation resistor R4, and forms a compensation current I4 on the branch of the voltage compensation resistor R4 and the voltage compensation controllable switch tube 1103, that is, I4 = Vm / R4.

[0066] The compensation current I4 is output to the second current mirror 1105 for voltage compensation after passing through the first current mirror 1104 for voltage compensation. Assuming the current mirror ratio of the first current mirror 1104 for voltage compensation is K2, then the compensation current I5 formed at the input end of the first current mirror 1104 for voltage compensation is I5 = K2 * I4. Since the input end of the second current mirror 1105 for voltage compensation is also connected to the constant current source 1106, and the constant current source 1106 generates a constant current I6, therefore, the compensation current I7 formed at the input end of the second current mirror 1105 for voltage compensation is I7 = I6 - I5 = I6 - K2 * I4 = I6 - K2 * (Vm / R4).

[0067] The compensation current I7 forms an input voltage compensation current I3 after passing through the second current mirror 1105 for voltage compensation. Assuming the current mirror ratio of the second current mirror 1105 for voltage compensation is K3, then the formed input voltage compensation current is: I3 = K3 * I7 = K3 * (I6 - K2 * (Vm / R4)).

[0068] As can be seen from the above formula, the input voltage compensation circuit 110 with the above structure makes the formed input voltage compensation current I3 inversely related to the input voltage Vm.

[0069] The input voltage compensation current I3 generated by the above method is transmitted to the compensation voltage generation circuit 102, and the compensation voltage generation circuit 102 generates an input compensation voltage Vref4 according to a preset reference voltage Vref1 and the input voltage compensation current I3. Among them, the input compensation voltage Vref4 is inversely related to the input voltage compensation current I3.

[0070] As a possible implementation manner, the inverse relationship between the input compensation voltage Vref4 and the input voltage compensation current I3 can be achieved through the following method. The compensation voltage generation circuit 102 has the same structure as the compensation voltage generation circuit 102 in the first embodiment, and the structure will not be repeated here. On this basis, as Figure 7 shown, the output end of the second current mirror 1105 for voltage compensation in the input voltage compensation circuit 110 is connected to the first end of the compensation resistor R2 in the compensation voltage generation circuit 102.

[0071] On the basis described above, the compensation error amplifier 1021 clamps the preset reference voltage Vref1 received at its non-inverting input terminal to the first end of R1, so as to form a first compensation current Ia between the inverting input terminal of the compensation error amplifier 1021, the compensation resistor R1 and the ground terminal, and form a compensation generation current Ib between the external power supply VDD, the compensation controllable switch 1022 and the compensation resistor R2. Since the output terminal of the voltage compensation second current mirror 1105 is connected to the first end of the compensation resistor R2 in the compensation voltage generation circuit 102, therefore, the input voltage compensation current I3 flows into from the first end of the compensation resistor R2, and further makes the compensation generation current Ib equal to the current difference between the first compensation current Ia and the input voltage compensation current I3, that is, Ib = Ia - I3.

[0072] Since the second end of the compensation resistor R2 is connected to the inverting input terminal of the error amplification circuit 20, therefore, the formed input compensation voltage Vref4 = Vref1 + Ib * R2 = Vref1 + (Ia - I3) * R2, and further generates an input compensation voltage Vref4 that is inversely related to the input voltage compensation current I3.

[0073] Based on the above, it can be obtained that the input voltage compensation current I3 is inversely related to the input voltage Vm, and the input compensation voltage Vref4 is inversely related to the input voltage compensation current I3, and further makes the input compensation voltage Vref4 positively related to the input voltage Vm.

[0074] The previously generated input compensation voltage Vref4 is transmitted to the inverting input terminal of the error amplification circuit 20. The error amplification circuit 20 generates an error signal Veao based on the output voltage Vout sampled at the non-inverting input terminal and the input compensation voltage Vref4 received at the inverting input terminal, and transmits it to the modulation circuit 30. The modulation circuit 30 adjusts the output voltage based on this error signal Veao. Among them, the manner in which the modulation circuit 30 adjusts the output voltage based on the error signal Veao is the same as the modulation manner of the modulation circuit 30 in the first embodiment, and will not be elaborated here.

[0075] Since the voltage at the non-inverting input terminal of the error amplification circuit 20 changes synchronously with the change of the voltage at the inverting input terminal, and the input compensation voltage Vref4 received at the inverting input terminal changes positively with the input voltage Vm, and further makes the error signal Veao output by the error amplification circuit 20 also change positively with the input compensation voltage Vref4 received at the inverting input terminal. Furthermore, the modulation circuit 30 controls the output voltage to change in the same way as the input voltage Vm based on the error signal Veao, and further compensates for the change of the output voltage Vout that is originally inversely related to the input voltage due to the change of the input voltage Vm, so as to control the output voltage to remain basically unchanged, and further eliminate or reduce the influence of the change of the input voltage on the output voltage, and realize the constant voltage output of the power supply.

[0076] According to the foregoing principle, the following is an illustration by way of example:

[0077] When the input voltage Vm decreases, since the input voltage compensation current I3 varies inversely with the input voltage Vm, the generated input voltage compensation current I3 increases; since the input compensation voltage Vref4 varies inversely with the input voltage compensation current I3, the input compensation voltage Vref4 decreases; since the voltage at the non-inverting input terminal of the error amplification circuit 20 changes synchronously with the change of the input compensation voltage Vref4 at the inverting input terminal, the voltage received by the non-inverting input terminal of the error amplification circuit 20 decreases, causing the output signal Veao of the error amplification circuit 20 to decrease, and further causing the output voltage Vout to be correspondingly adjusted downward based on the output signal Veao, resulting in a decrease in the output voltage Vout, thereby compensating for the originally increased output voltage Vout due to the decrease in the input voltage Vm, so as to control the output voltage to remain basically unchanged, and further eliminating or reducing the influence of the change in the input voltage on the output voltage, realizing the constant voltage output of the power supply. It should be noted here that the above example is for the scenario where the input voltage Vm decreases, and the principle of the scenario where the input voltage Vm increases is similar to the above and will not be elaborated here.

[0078] As a possible implementation manner, as Figure 6 and 7 shown, the aforementioned input voltage sampling sub-circuit 1101 may include a sampling resistor R7 and a sampling resistor R8. The first end of the sampling resistor R7 is used to receive the input voltage Vm, the second end of the sampling resistor R7 is grounded through the sampling resistor R8, and the non-inverting input terminal of the voltage compensation error amplifier 1102 is connected to the second end of the sampling resistor R7, so that the divided voltage Vx of the input voltage Vm sampled by the input voltage sampling sub-circuit 1101 is input to the non-inverting input terminal of the voltage compensation error amplifier 1102. On this basis, the aforementioned compensation current I4 is equal to Vx / R4 at this time.

[0079] In an alternative implementation manner of this embodiment, as Figure 8 shown, the output voltage control circuit of this embodiment may also include a modulation circuit 30 and a voltage sampling circuit 40, where the structures of the modulation circuit 30 and the voltage sampling circuit 40 are the same as those described in the first embodiment and will not be elaborated here.

[0080] Based on the foregoing modulation circuit 30, when the input voltage Vm decreases, the output voltage Vout increases. The increase in the output voltage Vout causes the output signal Veao of the error amplifier circuit 20 to increase. On the one hand, the increase in the output signal Veao causes the slope of the ramp compensation voltage signal RAW formed by superimposing it on the sampling voltage VL of the peak current to increase, thereby causing the modulation signal d to decrease. The decreased modulation signal d causes the duty cycle of the controllable switch Q1 to decrease, and thus the output voltage controlled by the controllable switch Q1 to decrease;

[0081] On the other hand, the decreased input voltage Vm is transmitted to the input voltage compensation circuit 110 to generate an input voltage compensation current I3. Since the load compensation current I3 is inversely related to the input voltage Vm, the input voltage compensation current I3 increases. Since the input compensation voltage Vref4 is inversely related to the input voltage compensation current I3, the input compensation voltage Vref4 decreases. Since the voltage at the positive input terminal of the error amplifier circuit 20 changes synchronously with the input compensation voltage Vref4 at the negative input terminal, the voltage at the positive input terminal of the error amplifier circuit 20 decreases, causing the output signal Veao of the error amplifier circuit 20 to decrease, thereby controlling the output voltage to remain constant by adjusting the magnitude of the modulation signal d.

[0082] Third Embodiment

[0083] This embodiment designs an output voltage control circuit for eliminating or reducing the influence of load current and input voltage changes on the output voltage, and thus achieving a constant voltage output of the power supply.

[0084] As Figure 9 and Figure 10 shown, the output voltage control circuit includes a compensation circuit 10 and an error amplifier circuit 20. The compensation circuit 10 includes a load current compensation circuit 101, an input voltage compensation circuit 110, and a compensation voltage generation circuit 102. The input terminal of the load current compensation circuit 101 is connected to the output terminal of the error amplifier circuit 20, and the output terminal of the load current compensation circuit 101 is connected to the input terminal of the compensation voltage generation circuit 102.

[0085] The input terminal of the input voltage compensation circuit 110 is used to receive the input voltage Vm. The output terminal of the input voltage compensation circuit 110 is connected to the input terminal of the compensation voltage generation circuit 102. The output terminal of the compensation voltage generation circuit 102 is connected to the negative input terminal of the error amplifier circuit 20. The positive input terminal of the error amplifier circuit 20 is used to sample the output voltage, and the output terminal of the error amplifier circuit 20 is used to be connected to the modulation circuit 30.

[0086] For the output voltage control circuit designed above, the load current compensation circuit 101 generates a load compensation current I1 according to the error signal Veao output by the error amplification circuit 20; the input voltage compensation circuit 110 generates an input voltage compensation current I3 according to the input voltage Vm. The load compensation current I1 and the input voltage compensation current I3 are transmitted to the compensation voltage generation circuit 102, so that the compensation voltage generation circuit 102 generates a compensation voltage Vref5 according to a preset reference voltage Vref1, the load compensation current I1, and the input voltage compensation current I3. The compensation voltage Vref5 is transmitted to the inverting input terminal of the error amplification circuit 20.

[0087] Among them, the error signal Veao is inversely related to the load current. The load compensation current I1 formed by the load current compensation circuit 101 is positively related to the error signal Veao, and the generated compensation voltage Vref5 is inversely related to the load compensation current I1, so that the load current is positively related to the compensation voltage Vref5. Among them, the implementation manner in which the load compensation current I1 is positively related to the error signal Veao is the same as that in the first embodiment, and the implementation manner in which the compensation voltage Vref5 is inversely related to the load compensation current I1 is the same as the implementation manner in which the load compensation voltage Vref2 is inversely related to the load compensation current I1 in the first embodiment.

[0088] The input voltage compensation current I3 formed by the input voltage compensation circuit 110 is inversely related to the input voltage Vm, and the input voltage compensation current I3 is inversely related to the compensation voltage Vref5, so that the input voltage Vm is positively related to the compensation voltage Vref5. Among them, the implementation manner in which the input voltage compensation current I3 is positively related to the input voltage Vm is the same as that in the second embodiment, and the implementation manner in which the input voltage compensation current I3 is inversely related to the compensation voltage Vref5 is the same as the implementation manner in which the input voltage compensation current I3 is inversely related to the input compensation voltage Vref4 in the second embodiment.

[0089] Assume that the load current increases and the input voltage also increases. First, the increase in the load current causes the error signal Veao to decrease. The load compensation current I1 is positively related to the error signal Veao. Therefore, the load compensation current I1 also decreases, and the compensation voltage Vref5 is inversely related to the load compensation current I1. Therefore, the compensation voltage Vref5 increases.

[0090] When the input voltage Vm increases, since the input voltage compensation current I3 is inversely correlated with the input voltage Vm, the input voltage compensation current I3 decreases; and since the compensation voltage Vref5 is inversely correlated with the input voltage compensation current I3, the compensation voltage Vref5 increases. In this way, the degree of increase in the compensation voltage Vref5 transmitted to the error amplifier circuit 20 is the sum of the load current change and the input voltage change. The increased compensation voltage Vref5 is transmitted to the inverting input terminal of the error amplifier circuit 20. Since the voltage at the non-inverting input terminal of the error amplifier circuit 20 changes synchronously with the voltage at the inverting input terminal, the voltage sampled at the non-inverting input terminal increases, prompting the error signal Veao output by the error amplifier circuit 20 to also increase. As a result, the modulation circuit 30 increases the output voltage Vout according to the increased error signal Veao, thereby eliminating or reducing the situation where the output voltage decreases due to an increase in the load current and an increase in the input voltage, and achieving a constant output of the output voltage of the power supply. Among them, when the load current decreases and the input voltage decreases, the principle is similar and will not be elaborated here.

[0091] It should be noted here that the load current compensation circuit 101 and the compensation voltage generation circuit 102 in this embodiment are the same as those in the first embodiment, and the input voltage compensation circuit 110 in this embodiment is the same as that in the second embodiment, which will not be elaborated here.

[0092] Based on the above structure, the compensation voltage Vref5 = Vref1 + (Ia - I1 - I3) * R2.

[0093] Fourth Embodiment

[0094] The present application provides a constant voltage output system, as Figure 11 shown. The constant voltage output system includes a rectification module 1, a constant voltage control chip 2, and a buck conversion module 3. The constant voltage control chip 2 includes the output voltage control circuit 4 described in the first embodiment or the second embodiment or the third embodiment.

[0095] The input terminal of the rectification module 1 is used to receive alternating current. The output terminal of the rectification module 1 is coupled to the constant voltage control chip 2 and the buck conversion module 3. The output terminal of the buck conversion module 3 is connected to the non-inverting input terminal of the error amplifier circuit 20. A controllable switch Q1 can be provided in the constant voltage control chip 2. The duty cycle of the controllable switch Q1 determines the voltage magnitude output by the buck conversion module 3 to the load, that is, determines the magnitude of the output voltage Vout. The output terminal of the error amplifier circuit 20 is connected to the control terminal of the controllable switch Q1, so that the constant voltage control chip 2 adjusts the output voltage Vout according to the output voltage control circuit 4 inside it.

[0096] The constant-voltage output system designed above. The rectification module 1 rectifies and converts the alternating current V (which can be the commercial power supply of 220V) into the input voltage Vm. The input voltage Vm is transmitted to the buck conversion module 3 for buck conversion and then provides the output voltage Vout to the external load. The output voltage Vout adjusted by the solution of this application is the voltage output to the load at both ends of the buck conversion module 3. This output voltage Vout is fed back to the positive-phase input terminal of the error amplification circuit 20 in the constant-voltage control chip 2, so that the error amplification circuit 20 in the constant-voltage control chip 2 controls and adjusts the output voltage in the manner of the first embodiment or the second embodiment or the third embodiment.

[0097] When the constant-voltage control chip 2 has the input voltage compensation circuit 110 in the second embodiment or the third embodiment, the input voltage Vm will also be transmitted to the input voltage compensation circuit 110 in the constant-voltage control chip 2, and then based on the manner of the second embodiment or the third embodiment, eliminate or reduce the influence of the change of the input voltage Vm on the output voltage Vout.

[0098] As a possible implementation manner, the error amplification circuit 20 can be connected to the control terminal of the controllable switch tube Q1 through the modulation circuit 30. The modulation circuit 30 outputs the corresponding modulation signal d based on the error signal output by the error amplification circuit 20 and transmits it to the control terminal of the controllable switch tube Q1, thereby controlling the duty cycle of the controllable switch tube Q1 to control the output voltage Vout and thus realizing constant-voltage output. In addition, it should be noted here that the sampling voltage VL of the aforementioned peak current is the Figure 11 sampling voltage at point A in

[0099] In the description of this application, it should be noted that the orientation or positional relationship indicated by terms such as "inside", "outside", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is usually placed during use. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, so it cannot be understood as a limitation to this application. In addition, terms such as "first", "second", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0100] It should also be noted that unless otherwise clearly specified and limited, the terms "set", "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific situations.

[0101] The above are only the embodiments of the present application and are not intended to limit the protection scope of the present application. For those skilled in the art, various changes and modifications can be made to the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. An output voltage control circuit, characterized in that, it includes: a compensation circuit (10) and an error amplification circuit (20), and the compensation circuit (10) includes a load current compensation circuit (101) and a compensation voltage generation circuit (102); the load current compensation circuit (101) is configured to generate a load compensation current according to an error signal output by the error amplification circuit (20), and transmit the load generated current to the compensation voltage generation circuit (102); the compensation voltage generation circuit (102) is configured to generate a load compensation voltage according to a preset reference voltage and the load compensation current, and transmit the load compensation voltage to the inverting input terminal of the error amplification circuit (20); the error amplification circuit (20) is configured to output a corresponding error signal according to the output voltage received by the non-inverting input terminal and the load compensation voltage received by the inverting input terminal, and the error signal is used to correspondingly control the output voltage of the modulation circuit (30) to achieve a constant output of the output voltage; wherein, the load compensation voltage is inversely related to the load compensation current.

2. The output voltage control circuit according to claim 1, characterized in that, the input terminal of the load current compensation circuit (101) is connected to the output terminal of the error amplification circuit (20), the output terminal of the load current compensation circuit (101) is connected to the input terminal of the compensation voltage generation circuit (102), the output terminal of the compensation voltage generation circuit (102) is connected to the inverting input terminal of the error amplification circuit (20), the non-inverting input terminal of the error amplification circuit (20) is used for sampling the output voltage, and the output terminal of the error amplification circuit (20) is further used for connecting to the modulation circuit (30).

3. The output voltage control circuit according to claim 2, characterized in that, the compensation voltage generation circuit (102) includes a compensation error amplifier (1021), a compensation resistor R1, a compensation resistor R2, and a compensation controllable switch tube (1022); the non-inverting input terminal of the compensation error amplifier (1021) is used for receiving the preset reference voltage, the inverting input terminal of the compensation error amplifier (1021) is respectively connected to the first terminal of the compensation resistor R1, the first terminal of the compensation resistor R2, and the output terminal of the load current compensation circuit (101), the second terminal of the compensation resistor R1 is grounded, the second terminal of the compensation resistor R2 is respectively connected to the inverting input terminal of the error amplification circuit (20) and the first terminal of the compensation controllable switch tube (1022), the output terminal of the compensation error amplifier (1021) is connected to the control terminal of the compensation controllable switch tube (1022), and the second terminal of the compensation controllable switch tube (1022) is connected to an external power supply; The compensation error amplifier (1021) is configured to clamp the preset reference voltage to the first end of the compensation resistor R1, form a first compensation current among the inverting input terminal of the compensation error amplifier (1021), the compensation resistor R1, and the ground terminal, and generate a load compensation divided voltage according to the current difference between the first compensation current and the load compensation current and the compensation resistor R2, so as to generate the load compensation voltage according to the load compensation divided voltage and the preset reference voltage and transmit it to the inverting input terminal of the error amplification circuit (20).

4. The output voltage control circuit according to claim 2, wherein, the load current compensation circuit (101) includes a load compensation error amplifier (1011), a load compensation resistor R3, a load compensation controllable switch tube (1012), and a load compensation current mirror (1013); the non-inverting input terminal of the load compensation error amplifier (1011) is connected to the output terminal of the error amplification circuit (20), the inverting input terminal of the load compensation error amplifier (1011) is grounded through the load compensation resistor R3, the output terminal of the load compensation error amplifier (1011) is connected to the control terminal of the load compensation controllable switch tube (1012), the first terminal of the load compensation controllable switch tube (1012) is connected to the inverting input terminal of the load compensation error amplifier (1011), and the second terminal of the load compensation controllable switch tube (1012) is connected to the compensation voltage generation circuit (102) through the load compensation current mirror (1013); the load compensation error amplifier (1011) is configured to clamp the voltage of the error signal to the first end of the load compensation controllable switch tube (1012) to form a second compensation current on the branch of the load compensation resistor R3 and the load compensation controllable switch tube (1012) and output it to the load compensation current mirror (1013); the load compensation current mirror (1013) is configured to generate the load compensation current according to the corresponding current mirror ratio and the second compensation current.

5. The output voltage control circuit according to claim 2, wherein, the output voltage control circuit further includes a modulation circuit (30), the input terminal of the modulation circuit (30) is connected to the output terminal of the error amplification circuit (20), and the output terminal of the modulation circuit (30) is used to be connected to the controllable switch tube (Q1); the modulation circuit (30) is configured to output a corresponding modulation signal according to the sampling voltage of the peak current and the error signal, and the modulation signal is used to adjust the duty cycle of the controllable switch tube (Q1), so as to correspondingly adjust the output voltage to achieve constant voltage output, wherein the duty cycle of the controllable switch tube (Q1) is positively correlated with the modulation signal.

6. The output voltage control circuit according to any one of claims 1-5, wherein, the load compensation current is inversely correlated with the load current, and the error signal and the output voltage are positively correlated with the load compensation voltage.

7. The output voltage control circuit according to claim 1, wherein, the compensation circuit (10) further includes an input voltage compensation circuit (110); the input voltage compensation circuit (110) is configured to generate an input voltage compensation current according to the input voltage and transmit the input voltage compensation current to the compensation voltage generation circuit (102); the compensation voltage generation circuit (102) is further configured to generate a compensation voltage according to the preset reference voltage, the load compensation current, and the input voltage compensation current and transmit the compensation voltage to the inverting input terminal of the error amplification circuit (20).

8. An output voltage control circuit, wherein, it includes: a compensation circuit (10) and an error amplification circuit (20), the compensation circuit (10) includes an input voltage compensation circuit (110) and a compensation voltage generation circuit (102); the input voltage compensation circuit (110) is configured to generate an input voltage compensation current according to the input voltage and transmit the input voltage compensation current to the compensation voltage generation circuit, and the input voltage is the sampled voltage corresponding to the bus voltage; the compensation voltage generation circuit (102) is configured to generate an input compensation voltage according to the preset reference voltage and the input voltage compensation current and transmit the input compensation voltage to the inverting input terminal of the error amplification circuit (20); the error amplification circuit (20) is configured to output a corresponding error signal according to the output voltage received by the non-inverting input terminal and the input compensation voltage received by the inverting input terminal, and the error signal is used to correspondingly adjust the output voltage of the modulation circuit (30) to control the constant output of the output voltage.

9. The voltage control circuit according to claim 8, wherein, the input voltage compensation circuit (110) includes a voltage compensation error amplifier (1102), a voltage compensation resistor R4, a voltage compensation controllable switch tube (1103), a voltage compensation first current mirror (1104), a voltage compensation second current mirror (1105), and a constant current source (1106); the non-inverting input terminal of the voltage compensation error amplifier (1102) is used to sample the input voltage, the inverting input terminal of the voltage compensation error amplifier (1102) is grounded through the voltage compensation resistor R4, and the output terminal of the voltage compensation error amplifier (1102) is connected to the control terminal of the voltage compensation controllable switch tube (1103); the first terminal of the voltage compensation controllable switch tube (1103) is grounded through the voltage compensation resistor R4, the second terminal of the voltage compensation controllable switch tube (1103) is connected to the input terminal of the voltage compensation first current mirror (1104), the output terminal of the voltage compensation first current mirror (1104) is respectively connected to the first terminal of the voltage compensation second current mirror (1105) and the constant current source (1106), the second terminal of the constant current source (1106) is grounded, and the output terminal of the voltage compensation second current mirror (1105) is connected to the input terminal of the compensation voltage generation circuit (102).

10. A constant voltage output system, characterized in that, the system includes: a rectification module (1), a constant voltage control chip (2), and a buck conversion module (3), and the constant voltage control chip (2) includes the output voltage control circuit described in any one of claims 1-9; the input end of the rectification module (1) is used to receive alternating current, the output end of the rectification module (1) is coupled to the constant voltage control chip (2), a controllable switch tube (Q1) is arranged in the constant voltage control chip (2), the output end of the rectification module (1) is coupled to the buck conversion module (3) through the controllable switch tube (Q1), the output end of the buck conversion module (3) is connected to the positive phase input end of the error amplification circuit (20), and the output end of the error amplification circuit (20) is connected to the controllable switch tube (Q1) to control the constant output of the output voltage.

Images